The present invention relates to the field of semiconductor device contact pads and, more particularly, relates to the enhancement of such semiconductor device contact pads to withstand the forces of probing and bonding.
Semiconductor devices such as integrated circuit chips and the like typically have contact pads for connection to a conventional package. Electrical connections can be made by a variety of means between these contact pads and the package. A robust contact pad for wire bonding would be desirable.
Moreover, as part of the semiconductor device manufacturing process, the contact pads are probed for electrical testing, in some cases a number of times. As noted in Wojnarowski et al. U.S. Pat. No. 5,391,516, the disclosure of which is incorporated by reference herein, such probing can result in varying degrees of probe damage to the contact pads. Where the wiring of the semiconductor device is copper, damage to the contact pad can expose the copper wiring to the atmosphere, resulting in the degradation of the electrical properties of such exposed copper wiring and hence the semiconductor device as well. Accordingly, it would be desirable to have a robust contact pad to withstand the rigors of probing as well.
Various solutions have been proposed for enhancing the reliability and robustness of semiconductor device contact pads.
Chen et al. U.S. Pat. No. 6,350,667, the disclosure of which is incorporated by reference herein, discloses a method of improving contact pad adhesion wherein a thin (50 to 80 angstroms) aluminum layer is inserted between a tantalum nitride barrier layer and the underlying copper wiring. The object of this invention is to improve the adhesion of the contact pad metal stack.
Hayashi et al. U.S. Pat. No. 5,523,626, the disclosure of which is incorporated by reference herein, discloses a titanium nitride/titanium/titanium nitride composite adhesion layer for bonding the aluminum contact pad to the upper interlayer insulation layer. The object of this invention is to improve the adhesion of the aluminum contact pad to the interlayer insulation layer.
Ma et al. U.S. Published Patent Application U.S. 2002/0068385, the disclosure of which is incorporated by reference herein, discloses an aluminum contact pad anchored to the underlying structure by tungsten or titanium vias. The object of this invention is to avoid delamination of the contact pad.
Pozder et al. U.S. Published Patent Application U.S. 2001/0051426, the disclosure of which is incorporated by reference herein, discloses a composite contact pad over a copper wiring level comprising dielectric columns within the contact pad area and aluminum over and between the dielectric columns. There is also a barrier layer such as tantalum, titanium, chromium or nitrides thereof to prevent contact between the aluminum contact pad and the copper wiring. The object of this invention is to have a mechanically robust contact pad to withstand test and probe operations.
In view of the various solution proposed by those skilled in the art, it is a purpose of the present invention to have a semiconductor device contact pad and method of forming therefore that does not have the drawbacks or shortcomings of the prior art.
It is a further purpose of the present invention to have a semiconductor device contact pad and method of forming therefore which is robust and able to withstand the rigors of wire bonding and test and probing operations.
It is yet another purpose of the present invention to have a semiconductor device contact pad and method of forming therefore which protects the underlying copper wiring.
These and other purposes of the present invention will become more apparent after referring to the following description of the invention considered in conjunction with the accompanying drawings.